Roles of RelB in tuning inflammatory and innate immune responses

项目总结/摘要 在这个项目中，我们将寻求更好地了解为什么以及如何小鼠品系缺乏NFκB RelB 作为非经典NFκB通路的主要效应物， 自身免疫性疾病鉴于以前的研究集中在NFκB反应基因，我们的无偏 转录组学测量（初步结果）显示，RelB缺陷的巨噬细胞和树突状细胞 细胞显示干扰素刺激基因（ISG）的显著超表达，这是由于 干扰素-β抗原呈递细胞中I型干扰素调节系统的过度活性确实可以解释 RelB基因敲除小鼠中T细胞介导的自身免疫表型。拟议项目涉及 总体假设，RelB作为一个关键的信号节点，微调炎症和 干扰素介导的反应从先天性免疫过渡到适应性免疫。 在第一个具体目标中，我们将首先表征在小鼠中RelB对干扰素基因表达的控制。 巨噬细胞和树突状细胞，不仅在RelB基因敲除，而且在自然发生的脾DC，显示 RelB的低或高表达（使用新的RelB-Venus报道基因）。我们将研究是否减少 干扰素系统的超活性在遗传上将抑制RelB-/-小鼠的自身免疫表型。 在第二个具体目标中，我们将描述RelB如何调节I型干扰素的机制 应答使用新的RelB-DNA结合突变体（RelBdb/db），我们将区分染色质结合的 vs.细胞质机制初步结果表明，（i）IRF 3的过度激活可能是由以下因素介导的： RelB对RelA的细胞质抑制，无论是通过直接结合还是通过稳定RelA捕获Iκ B体， 和（ii）RelB：p50可通过与IRF 3竞争结合G-IRE而直接抑制IFNβ表达 （Cheng等2011）。这些机制将在拟议的研究中描述。

PROJECT SUMMARY/ABSTRACT In this project we will seek a better understanding of why and how mouse strains lacking the NFκB RelB protein, known as the primary effector of the non-canonical NFκB pathway, develop severe inflammatory and auto-immune disease. Whereas previous studies focused on NFκB response genes, our unbiased transcriptomic measurements (preliminary results) revealed that RelB-deficient macrophages and dendritic cells show dramatic hyper-expression of interferon stimulatory genes (ISGs) due to hyper-expression of interferon-β. Hyper-activity of the type I IFN regulatory system in antigen-presenting cells may indeed explain the T-cell mediated auto-immune phenotype in RelB knockout mice. The proposed project addresses the overarching hypothesis that RelB functions as a critical signaling node that fine-tunes inflammatory and interferon-mediated responses during the transition from innate to adaptive immunity. In the first Specific Aim, we will first characterize the control of interferon gene expression by RelB in macrophages and dendritic cells, not only in RelB knockouts but also naturally occurring splenic DCs that show either low or high expression of RelB (using a novel RelB-Venus reporter). We will examine whether reducing the hyper-activity of the interferon system genetically will suppress the auto-immune phenotype of RelB-/- mice. In the second Specific Aim, we will characterize the mechanism of how RelB regulates type I interferon responses. Using a novel RelB-DNA binding mutant (RelBdb/db), we will distinguish between chromatin-bound vs. cytoplasmic mechanisms. Preliminary results suggest that (i) hyper-activation of IRF3 may be mediated by cytoplasmic inhibition by RelB of RelA, either by direct binding or via stabilizing the RelA-trapping IκBsome, and that (ii) RelB:p50 may directly inhibit IFNβ expression by competing with IRF3 for binding to the G-IRE (Cheng et al 2011). These mechanisms will be delineated in the proposed studies.